FIGURE 3.

Ca²⁺-activated maximal tension and ATPase activity in detergent-skinned rat cardiac muscle fiber bundles reconstituted with recombinant rat cTnT and fsTnT. After reconstitution, Ca²⁺-activated maximal tension and ATPase activity (21,22) were measured in activation buffer at pCa 4.3. Control untreated muscle fibers (control), cTnT+cTnI+cTnC reconstituted muscle fibers (cTnT), and fsTnT+cTnI+cTnC reconstituted muscle fibers (fsTnT). (A) Effect on Ca²⁺-activated maximal tension at SL of 2.2 μm. (B) Effect on Ca²⁺-activated maximal tension and ATPase activity at SL of 2.2 μm. Residual Ca²⁺-activated tension (pCa 4.3) measured after treatment with either cTnT+cTnI or fsTnT+cTnI was minimal (∼1.0 mN/mm²). Number of determinations is at least 10 for each. The asterisk symbol (*) indicates a result significantly different from control (P < 0.001).